The present invention relates generally to industrial robot systems used for fabricating components for use in an image forming system, and more particularly, relates to the use of a reference position system with the industrial robot system. 10 Many industrial robot systems utilized to perform precision assembly of electronic devices such as, electronic devices containing multiple Light Emitting Diodes (LED) for use in image forming systems, such as scanners and printers, are capable of achieving a workpiece placement accuracy of between 25 microns and 50 microns. Nonetheless, in a high volume manufacturing setting, the component placement accuracy of the industrial robot deteriorates during use. For example, the stresses associated with repetitive movements cause thermal warming and cooling which significantly impacts the systems placement accuracy. As a result, workpiece placement accuracy of greater than 15 microns is difficult to achieve in a high volume manufacturing environment.
The conventional method and apparatus for achieving greater workpiece placement accuracy with an industrial robot system has been to use two fixed cameras located over the workpiece placement location. The two fixed cameras identify a desired workpiece placement location by imaging the desired placement location and the industrial robot to provide feedback correction data. The benefits of this technique include the negation of inaccuracies caused by thermal cycling, e.g., warming and cooling, and the correction of inherent industrial robot movement inaccuracies.
The use of two fixed cameras located over a workpiece placement location does not provide sufficient accuracy when placing multiple workpieces in a densely populated electronic device. Specifically, the two fixed cameras cannot accurately view multiple chips over the length or width of the populated substrate, and therefore, lacks the ability to align multiple workpieces relative to one another. As such, high workpiece density electronic devices requiring workpiece placement accuracy better than 15 to 25 microns is burdensome and oftentimes requires manual labor intervention to ensure accurate workpiece placement.
The present invention addresses the above described problems associated with conventional reference position apparatus for industrial robot systems by increasing an industrial robot""s workpiece placement accuracy to between about 5 microns and about 10 microns. This is accomplished by providing an imaging system sufficient to overcome inherent robot movement errors, as well as errors induced by the thermal cycling effects in a high volume manufacturing environment.
The system of the present invention includes a manipulator for moving the workpiece, an air bearing assembly, and an image referencing system disposed relative to the air bearing assembly for acquiring image data corresponding to the workpiece being moved by the manipulator. A workpiece source for housing a plurality of workpieces can also be provided.
According to one aspect, the image referencing system includes a plurality of image acquisition elements for acquiring image data corresponding to the workpiece. For example, the system can include a first image acquisition element for acquiring image data of a reference workpiece disposed on the substrate, and a second image acquisition element for acquiring image data of the workpiece being moved by the manipulator
According to another aspect, the manipulator includes a controller for controlling movement thereof. A feedback connection can be provided between the image referencing system and the controller for controlling movement of the manipulator based on the acquired image data.
The present invention also provides for a system for moving a workpiece having an air bearing assembly, a manipulator for moving the workpiece, and an imaging referencing system coupled to the air bearing assembly and adapted for movement therealong for acquiring image data of the workpiece being moved by the manipulator.
According to one aspect, the imaging reference system comprises a first image acquisition element for acquiring image data of the workpiece being moved by the manipulator, and a second image acquisition element for acquiring position reference data. Specifically, the second image acquisition element can acquire data of a fixed target disposed on a base, where the data corresponds to the location of the manipulator.
According to another aspect, the manipulator includes a controller for controlling movement of the manipulator, and the system includes a feedback connection disposed between the imaging reference system and the manipulator for controlling movement of the manipulator based upon the image data acquired from the first and second image acquisition elements.
The present invention also provides for a system for moving a workpiece having an air bearing assembly, and a manipulator coupled to the air bearing assembly for moving the workpiece, where the manipulator includes a controller for controlling movement thereof, and first and second image acquisition elements for acquiring image data corresponding to the workpiece.